Assessing Chronic Pain in Cats: The Grimace Scale

Cats are notoriously stoic and mask pain as an evolutionary survival strategy, making chronic pain one of the most under-recognised and under-treated welfare problems in companion cats. The Feline Grimace Scale (FGS) offers a validated, objective tool to assess pain from facial expressions.

Key Facts

The Feline Grimace Scale (FGS), validated in 2019, scores five facial action units: ear position, orbital tightening, muzzle tension, whisker change, and head position
Each action unit is scored 0 (absent), 1 (moderate), or 2 (obvious), giving a maximum score of 10; scores above 4 indicate pain requiring intervention
FGS has been validated for acute pain and is increasingly used to assess chronic pain in conditions like osteoarthritis, dental disease, and FLUTD
Feline osteoarthritis affects an estimated 90% of cats over 12 years old, but fewer than 10% receive analgesic treatment
Cats may still purr, eat, and groom while experiencing significant pain — these behaviours are unreliable indicators of comfort
Chronic pain in cats often manifests subtly: reduced jumping, altered gait, reluctance to use litter trays, or increased aggression
NSAIDs approved for long-term use in cats (such as meloxicam and robenacoxib) have transformed chronic pain management

Welfare Considerations

The chronic pain burden in the cat population is enormous and largely invisible. Owners and even veterinarians frequently miss pain because cats do not vocalise or limp conspicuously. Dental disease, affecting up to 70% of cats over three years, causes persistent oral pain that often goes untreated for years. Osteoarthritis in senior cats causes daily discomfort that restricts mobility and quality of life. The FGS gives owners and clinicians a standardised language to identify and track pain, transforming subjective impressions into measurable scores. Welfare-focused veterinary practice incorporates regular pain assessments at check-ups, especially for senior cats, rather than waiting for owners to report obvious symptoms.

What You Can Do

Learn the five Feline Grimace Scale action units — free resources including a scoring app are available from the FGS team at the University of Montreal
Schedule annual veterinary checks for your cat that explicitly include a pain assessment, especially from age 7 onwards
Provide environmental modifications for potentially painful cats: ramps, low-sided litter trays, raised food bowls, and warm resting spots
Ask your vet about long-term analgesic options if your senior cat shows any signs of reduced mobility or altered behaviour
Support feline pain research by participating in studies through veterinary school feline health programmes